This is a new application for a Mentored Quantitative Research Development Award (K25). The applicant, Douglas Steinley, a quantitative psychologist in the Department of Psychological Sciences at the University of Missouri-Columbia, proposes a period of career development and research designed to focus his skills in methodological development on pressing problems in alcohol related research. Under the mentorship of Kenneth J. Sher, Curator's Professor of Psychological Sciences at the University of Missouri-Columbia, the applicant will become familiar with theoretical and substantive issues concerning alcohol abuse and alcoholism. Additionally, the mentor will guide the candidate with respect to grantmanship with the ultimate goal being the transition of the applicant to an independent investigator. The process includes a detailed career development plan that includes a didactic component (e.g., alcohol research related coursework and workshops) and an emersion into a provenly successful alcohol research environment (e.g., immediate integration into the mentor's lab,interaction with other faculty members in the department conducting alcohol research, promoted collaboration with the nearby Midwest Alcoholism Research Center, etc.). With respect to his research plan, the applicant plans to apply his broad based methodological developments in classification/clustering to domain specific questions concerning discovering, verifying, and validating subtypes in alocohol research. The research plan includes components for investigating cross-sectional and longitudinal relationships among alchol use disorders in the context of co-occuring psychopathology and human development. Furthermore, methodology will be developed specifically to address problems in these areas. Using existing data sets (NIAAA's NESARC data) and data sets currently under construction by the proposed mentor, the applicant proposes to begin a research program that develops new methodology and coordinates existing, but likely unknown to alcohol researchers, methodology in the context of alcohol research. The research is relevant to public health in that the applicant will develop new methodological techniques that are appropriate for alcohol research. Furthermore, a set of standards will be developed to validate existing results and future findings in alcohol research, providing applied researchers the ability to discern when to apply specific analytic techniques.